This invention relates to an apparatus for separating an oily cutting liquid from combined cutting liquids including both a water-soluble cutting liquid and the oily cutting liquid.
In a conventional machine tool, the cutting liquids are used for a tool or tools when a workpiece is machined. Either the water-soluble cutting liquid or the oily cutting liqiid is used in view of workpiece materials and types of tools to be used.
After the water-soluble cutting liquid and the oily cutting liquid are used at the machine tool, both of them are contained in a single tank. In this case, therefore, those different cutting liquids are combined in the tank.
If the used water-soluble cutting liquid is desired to be again used, the used water-soluble cutting liquid must be separated from the used oily cutting liquid. The used oily cutting liquid is normally thrown away.
The operation of separating the used water-soluble cutting liquid from the used oily cutting liquid is very important in order to increase the purity of the water-soluble cutting liquid to be recycled as well as in order to prevent the water-soluble cutting liquid from being decomposed.
It is well-known that the oily cutting liquid floats on the water-soluble cutting liquid due to a difference between their specific gravities so as to constitute two liquid layers. By taking this into consideration, a drain port is formed in a bottom portion of the tank. An operator is used to open regularly the drain port so that the water-soluble cutting liquid can be drained through the drain port to a predetermined level. As a result, the water-soluble cutting liquid is separated from the oily cutting liquid.
In such a conventional manner, an operator must pay attention to a liquid level in the tank. In addition, it is very difficult to separate precisely the water-soluble cutting liquid from the oily cutting liquid in the tank. Further, it is not unusual that the oily cutting liquid to be disposed remains in the tank. In such a case, it is extremely difficult to take out the oily cutting liquid from the tank.